Hi thanks for your question.
Your 83 year old member is daibetic and hypertensive.Diabetics are more prone to infection and that too in old age when immunity is decreased.She has developed infection of the lungs called as pneumonia
.The symptoms( increased temperature ,tightness in chest and feeling unwell) she is having most probably could be due to pneumonia.The swollen legs could be due to cardiac failure which may be associated with pneumona ,diabetes
and increasedblood pressure.
Hope this answers your question.